Processing of Diamonds by Short Pulse Lasers

A study on the processing of diamonds using two kinds of short pulse lasers was conducted. Diamonds used are single crystals synthesized at high temperature and high pressure, and platelet single crystal synthesized by the chamber-flame CVD method. Polycrystalline diamond film synthesized by the CVD method was also used. ArF excimer laser with pulse width of 20 nanoseconds, and a Ti-sapphire laser with pulse width of 150 femtoseconds were used. A laser beam was introduced to focus on the surface of the specimen in air. Results obtained are summarized as follows. In excimer laser processing, (1) only a slight difference the grooving properties is observed for various single-crystal diamonds, and (2) polycrystalline diamond is processed more easily than single-crystal diamonds. In the processing using the femtosecond laser, (1) combinations of high output energy and low beam scan speed produce a high-quality groove with straight wall and sharp edge, (2) other combinations of the parameters produce grooves having defects such as crack formation and/or attachment of by-product both in and outside of the groove, or having a narrow neck on the upper portion of the groove, and (3) controlled processing conditions can realize clean processing with no heat-affected zones on the surface of the groove.